Well-Tempered Clavier
The Well-Tempered Clavier (German Das Wohltemperierte Klavier) refers to two volumes of preludes and fugues by Johann Sebastian Bach. Each volume contains a prelude and a fugue in every major and minor key, adding up to 24 pairs total. The order of keys begins from C Major, followed by C Minor, then proceeds up by half-step until the 24th in B Minor.
Bach compiled the first part in 1722, followed by the second in 1742, intending them for the study of keybard playing. They were not published until the 19th century, but after Bach's death they were well-known by some influential Leipzig-based keyboardists such as C. G. Neefe, who taught Beethoven in Bonn.[1] The Dutch ambassador and musical connoiseur Baron Gottfried van Swieten is credited with bringing the WTC to Vienna for the first time in 1777.[2] Because of Swieten's influence, it was known by Mozart. Later, both Frederic Chopin and Sergei Rachmaninoff claimed to have played a prelude and fugue from it every morning.
The first keyboard cycle to include all keys, the WTC inspired several later composers to compose cycles of preludes (with or without fugues). Chopin's Preludes (Op. 28) are particularly beloved, and Rachmaninoff eventually published 24 preludes (Op. 3/2, Op. 23, Op. 32). Dmitri Shostakovich was so taken with the idea that he published a set of 24 preludes early in his career (Op. 34), and then writing a seperate set of 24 preludes and fugues (Op. 87) in the 1950's, both sets following Chopin's system of progressing through the circle of fifths rather than Bach's half-steps.